Point-to-point wireless systems using microwaves, millimeter waves or the like are well known. In a point-to-point wireless system, two communication apparatuses perform digital communication via a point-to-point wireless link. To be more specific, each of the communication apparatuses is equipped with a directional antenna in order to communicate with a counterpart apparatus using a point-to-point wireless technology and forms a directional beam toward the counterpart apparatus. In this way, a point-to-point wireless link is established between the two communication apparatuses. In the specification, each of the two communication apparatuses constituting the point-to-point wireless system, i.e., a communication apparatus that communicates with a counterpart apparatus using the point-to-point wireless technology, will be referred to as a point-to-point wireless apparatus.
Compared to wired connections using optical fibers, point-to-point radio systems have many advantages such as easy networking, low costs, and mitigation of conditions for an installation location of a base station. The point-to-point wireless systems are used, for example, in a mobile backhaul. The mobile backhaul indicates communication lines that connect base stations in a cellular communication system to a core network and communication lines that connect between the base stations.
Patent Literature 1 and 2 discloses point-to-point wireless apparatuses. The point-to-point wireless apparatus disclosed in Patent Literature 1 includes an antenna and a front-end device (Outdoor Unit (ODU)) that are installed outdoors and a back-end device (Indoor Unit (IDU)) that is installed indoors. The front-end device (ODU) primarily performs analog signal processing at the carrier frequency (radio frequency (RF) band) such as frequency up/down conversion and amplification. The back-end device (IDU) primarily performs baseband digital signal processing such as channel coding/decoding, interleaving/deinterleaving, and modulation/demodulation. The front-end device may be referred to as an RF unit. The back-end device may be referred to as a baseband unit.
On the other hand, the point-to-point wireless apparatus disclosed in Patent Literature 2 has a structure in which electronic equipment for performing point-to-point wireless communication with a counterpart apparatus is accommodated in one enclosure that can be installed outdoors. To be more specific, the point-to-point wireless apparatus disclosed in Patent Literature 2 has a structure in which a front-end electronic circuit module and a back-end electronic circuit module are accommodated in one enclosure. The front-end electronic circuit module includes circuits that perform analog signal processing at the RF band (e.g., frequency conversion and signal amplification). The back-end electronic circuit module includes circuits that perform baseband digital signal processing (e.g., channel coding and modulation/demodulation). The front-end electronic circuit module may be referred to as an RF circuit. The back-end electronic circuit module may be referred to as a baseband circuit.